High-rate rechargeable batteries with long cycle life at reasonable cost are of high demand for powering motor vehicle and as a source of renewal energy replacing fossil fuels. A known alternative would be Lithium-ion batteries but the number of complete charge/discharge cycles that the battery is able to support before its capacity falling under 80% of its original capacity is less than 2000 cycles. The expensiveness of Lithium-ion batteries is another disadvantage in addition to the flammability of the electrolytes.
Aluminum is always an attractive material for batteries for its low cost, low flammability and high-charge storage capacity. Scientists have invented high-performance aluminum battery that is fast charging, long lasting and relatively inexpensive. It is considered a safe alternative replacing existing storage devices. Aluminum has a specific capacity of 2980 mAh g−1 and volumetric capacity of 8046 mAh cm−3 which are higher than those of lithium. However secondary aluminum-based batteries are only possible in non-aqueous electrolytes with larger electrochemical stability window because aluminum re-deposition occurs at a more negative potential −1.68V vs. SHE. (Standard hydrogen electrode) In the earlier days only aqueous or high temperature molten salt system are used. One concern is that aluminum in neutral or acidic electrolyte has a potential of −1.68V vs. SHE, and when the potential reaches −1.23V, electrolysis of water occurs. This make aqueous electrolyte unsuitable for high-performance energy storage devices with redox potentials outside the stability window of water.
Ionic liquids are widely promoted as designer electrolytes. The key attraction of ionic liquid is the wide electrochemical stability window. Most ionic liquids show high thermal stability, non-flammability, non-volatility and lower vapor pressure. It has relatively low toxicity comparing to organic solvents.
The invention seeks to eliminate or at least to mitigate such shortcomings by providing a non-liquid electrolyte for use in a battery.